JP2001299925A - Catheter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a catheter free from the danger of breakage or separation of a soft tip part at the top. SOLUTION: This catheter 1 has a two-layer structure consisting of an inner layer 6 and outer layer 7 formed of resin. The tip of the outer layer 1 is integrated without having any joint surface and protruded ahead over the tip surface of the inner layer 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a medical catheter, and more particularly to a structure of a distal end portion and a manufacturing method thereof.

[0002]

2. Description of the Related Art FIG. 4 is an overall structural view of a conventional catheter, and FIG. 5 is a sectional view of a distal end portion thereof. FIG.
Is a graph of the rigidity at the tip.

The catheter 1 comprises a hub 2 serving as an insertion port for a contrast agent or a guide wire, a strain relief 3 for protecting a tube at a hub mounting portion, and a catheter tube 4. A soft tip 5 made of resin is joined. This soft tip 5 is for preventing invasion such as damage to blood vessels at the time of catheter insertion, and as shown in FIG.
Its stiffness drops sharply from the two-layer tube section. The catheter tube 4 has a two-layer structure of an inner layer 6 and an outer layer 7. The inner layer 6 is formed of a relatively hard and smooth resin in order to smoothly insert a guide wire or the like.
Is formed of a resin softer than the inner layer 6 in order to improve the followability to blood vessels. A sleeve-like soft tip 5 made of the same soft resin as the outer layer 7 and separate from the catheter tube 4 is joined to the distal end of the catheter tube 4 having such a two-layer structure by bonding, welding or fusion. . Accordingly, a joint surface 8 is formed between the distal end portion of the catheter tube 4 and the soft tip 5.

[0004]

However, since the conventional soft tip 5 provided at the distal end of the catheter is formed separately from the catheter tube 4 and joined thereto, the soft tip 5 is broken or detached from the joining surface 8. There was a risk of doing.

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above-mentioned prior art, and has as its object to provide a catheter in which a soft tip portion at a distal end portion is prevented from being broken or detached.

[0006]

In order to achieve the above object, the present invention provides a catheter having a two-layer structure of an inner layer and an outer layer made of a resin, wherein the distal end of the outer layer has an integral inner layer without having a joint surface. Provided is a catheter characterized by protruding forward from a distal end surface.

According to this structure, since the resin material of the outer layer at the tip of the tube protrudes toward the end of the inner layer, a separate soft tip is not used, so that a joining surface is not formed and the tube tip is formed. A flexible portion integral with the outer layer protrudes. Since the flexible protruding portion at the tip is integral with the outer layer, there is no possibility of breakage or detachment.

As a method for manufacturing such a catheter,
In the present invention, by preparing a base tube consisting of an inner layer and an outer layer having aligned end faces, covering the end of the tube with a heat-shrinkable tube, and heating the end to shrink the heat-shrinkable tube, Provided is a method for manufacturing a catheter, characterized in that an outer layer is made to protrude forward from a tip surface of an inner layer.

According to this structure, the heat-shrinkable tube is put on the distal end portion of the two-layer structure tube, and the heat-shrinkable tube is thermally shrunk. Can protrude forward from the inner layer end face.

[0010] In a preferred configuration example, the tip of the protruding outer layer is rounded or chamfered while the heat shrink tube is covered when the heat shrink tube is shrunk.

[0011] According to this structure, since the stretched outer layer tip is directly rounded or chamfered together with the heat-shrinkable tube by, for example, a mold at the same time as the heat-shrinkage, it is possible to smoothly damage the blood vessel without increasing the number of steps. It is possible to efficiently form a catheter having an arbitrary shape.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. 1 (A) to 1 (F) are cross-sectional views of a catheter end showing a manufacturing process of a catheter according to the present invention in order. First, according to a normal process, a catheter tube 4 including an inner layer 6 and an outer layer 7 is formed.
Is formed as a substrate tube, and the end surfaces thereof are aligned as shown in FIG. The catheter tube (base tube) 4 is formed by, for example, extruding a resin material from an extrusion screw and extruding through a mandrel of a mold. At this time, a conductive wire corresponding to the inner diameter of the tube is supplied through the center of the mandrel, and a resin material extruded from the periphery of the mandrel together with the conductive wire is formed to form a tube having a predetermined inner diameter. A relatively hard resin constituting the inner layer 6 is previously applied onto the conductor, and a soft resin constituting the outer layer is extruded from an extrusion screw to form two layers of resin on the conductor. . After cooling the resin, the central conducting wire is pulled out, whereby a two-layer catheter tube 4 composed of an inner layer 6 and an outer layer 7 is formed.

Next, as shown in FIG. 2B, a heat-shrinkable tube 9 is placed over the distal end portion of the catheter tube 4 and a core 10 made of a hard pipe or wire having a diameter corresponding to the inner diameter is inserted into the heat-shrinkable tube. Insert only the length corresponding to 9.

Thereafter, the heat-shrinkable tube 9 is heated while leaving the insertion-side end of the heat-shrinkable tube 9 slightly, and the heat-shrinkable tube 9 is shrunk in the radial direction. As a result, as shown in FIG.
Is pressed radially inward from the outside to reduce the diameter, and the resin of the outer layer 7 that is reduced and squeezed out projects beyond the tip end surface of the inner layer 6 to form a protruding portion 7a. In this case, since the core material 10 is inserted into the catheter tube 4,
A constant inner diameter is maintained without being crushed inward.

Next, as shown in (D), the heat-shrinkable tube 9 is removed while the core material 10 is left. The catheter tube 4 from which the heat-shrinkable tube 9 has been removed is inserted into a mold 11 and molded. Thereby, as shown in (E), the protruding portion 7a at the distal end of the catheter tube 4 is formed into a rounded smooth shape.

Thereafter, the catheter tube 4 is connected to the mold 11.
And the core material 10 is pulled out, as shown in (F), a reduced diameter portion 7b is formed at the tip of the outer layer 7, and the tip projects forward from the inner layer 6 to form an integral resin material with the outer layer 7. A two-layer catheter tube 4 on which the projection 7a is formed is obtained.

Instead of performing the round forming process on the protruding portion 7a of the outer layer by the mold 11, a rounding process or a chamfering process may be performed by polishing or grinding. By performing rounding or chamfering on the protruding portion 7a integral with the outer layer 7 in this manner, the contact with the blood vessel when the catheter is inserted is softened, the blood vessel is prevented from being damaged, and the invasiveness to the blood vessel is reduced.

Since the projecting portion 7a at the distal end of the catheter tube 4 is made of a material integral with the resin material of the outer layer 7, a joining surface is not formed unlike a conventional soft tip. There is no problem such as separation from the material or breakage.

FIG. 2 is a sectional view showing another embodiment of the method for producing a catheter according to the present invention. In this embodiment, the mold 11 is set in advance in the process of FIG.
At the same time, the projecting portion 7a is rounded by the mold 11 while the heat-shrinkable tube 9 covers the projecting portion. This simplifies the manufacturing process and efficiently forms a catheter tube. In this case, it is necessary to align the ends of the heat-shrinkable tube 9 and the outer layer 7 in advance.

FIG. 3 is an explanatory view of the configuration of still another embodiment of the present invention. This embodiment is similar to the embodiment shown in FIG.
The marker ring 12 is attached to the catheter tube 4 formed by
Is fitted. The marker ring 12 is used for imaging the catheter at the time of insertion and displaying the tip position of the catheter on a monitor. By mounting such a marker ring 12, the outer layer 7 swells outward together with the inner layer 6 at that portion, and a convex portion 7 c is formed outside the outer layer 7. In the present embodiment, the heat shrink tube 9
Due to the thermal shrinkage, the convex portion 7c is pressed and flattened, and the protruding portion is protruded toward the tip to form a protruding portion 7a. Therefore, in this embodiment, the reduced diameter portion 7b of the outer layer 7 as in the above embodiment is not formed, and the outer layer 7 remains at a constant outer diameter. Other manufacturing processes, configurations, and operational effects are the same as those of the above-described embodiment.

[0021]

As described above, according to the structure of the present invention, since the resin material of the outer layer at the tip of the tube protrudes toward the end of the inner layer, the joining can be performed without using a separate soft tip. Without forming a surface, a flexible portion integral with the outer layer protrudes from the distal end of the tube. Since the flexible protruding portion at the tip is integral with the outer layer, there is no possibility of breakage or detachment.

As a method of manufacturing such a catheter,
According to the present invention, a heat-shrinkable tube is put on the distal end portion of the two-layer structure tube and heat-shrinks it, so that the outer layer can be easily pressed from the outer peripheral side and stretched in the axial direction, so that the outer layer end portion becomes the inner layer end surface The catheter can be projected further forward, and a highly reliable catheter without breakage or detachment can be obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view of a catheter end showing a manufacturing process of a catheter according to the present invention in order.

FIG. 2 is a cross-sectional view showing another embodiment of the method for producing a catheter according to the present invention.

FIG. 3 is a configuration explanatory view of still another embodiment of the present invention.

FIG. 4 is an overall configuration diagram of a conventional catheter.

FIG. 5 is a cross-sectional view of the distal end portion of the catheter of FIG.

6 is a graph of the stiffness of the distal portion of the catheter of FIG.

[Explanation of symbols]

1: catheter, 2: hub, 3: strain relief,
4: catheter tube, 5: soft tip, 6: inner layer, 7: outer layer, 8: joining surface, 9: heat shrink tube, 1
0: core material, 11: mold, 12: marker ring

Claims (3)

[Claims] 1. A catheter having a two-layer structure of an inner layer and an outer layer made of a resin, wherein a distal end portion of the outer layer integrally projects without a joint surface and protrudes forward from the inner layer distal end surface. 2. A base tube comprising an inner layer and an outer layer having a uniform front end surface is prepared, a heat-shrinkable tube is put on the front end of the tube, and the heat-shrinkable tube is shrunk by heating the front end. The method for manufacturing a catheter according to claim 1, wherein the outer layer is made to protrude forward from a front end surface of the inner layer. 3. The method for manufacturing a catheter according to claim 2, wherein the tip of the protruding outer layer is rounded or chamfered while the heat-shrinkable tube is covered when the heat-shrinkable tube is shrunk. .